Tire having carcass section below the belt free from pulling tension

ABSTRACT

A method of making a pneumatic vehicle tire with a pull resistant belt for lateral stabilization of the tire and with a carcass having strength members extending from bead to bead at a substantially right angle with regard to the circumferential direction of the tire, those sections of the strength members which form said carcass and face toward said belt being free from pull stresses in the inflated condition of said tire.

Sept. 5, 1972 H. WITTNEBEN 3,539,333

TIRE HAVING CARCASS SECTION BELOW THE BELT v FREE FROM PULLING TENSION v Original Filed Dec. 7, 1966 III INVENTOR. fl w r70 I) M// 9 United States Patent Int. Cl. B29h 17/26 US. Cl. 156-133 2 Claims ABSTRACT OF THE DISCLOSURE A method of making a pneumatic vehicle tire with a pull resistant belt for lateral stabilization of the tire and with a carcass having strength members extending from bead to bead at a substantially right angle with regard to the circumferential direction of the tire, those sections of the strength members which form said carcass and face toward said belt being free from pull stresses in the inflated condition of said tire.

This is a division of copending application SN. 5 99,850, Wittneben, filed Dec. 7, 1966, now US. Pat. 3,532,150, Wittneben, issued Oct. 6, 1970, and belonging to the assignee of the present invention.

The present invention relates to a method of making a pneumatic vehicle tire with a pull-resistant belt for lateral stabilization and with a carcass of thread-shaped reinforcing inserts extending from bead to bead at a right angle or approximately a right angle with regard to the circumferential direction ofthe tire.

With heretofore known pneumatic tires of the above mentioned type, the so-called belted tire, it is the purpose of the carcass, as is also the case with belt-less tires, to absorb the forces caused by the inner pressure of the tire. In addition thereto, the heretofore known beltequipped pneumatic vehicle tires are so designed that the reinforcing inserts forming the carcass are subjected over their entire length from head to bead to a uniform pull- 1lnkg stress in the longitudinal direction of the thread or the It is an object of the present invention, by a special design of the carcass, so to influence the belt that it will be able to absorb relatively large forces necessary for obtaining an increased lateral stabilization.

It is a further object of this invention to provide a method of making a pneumatic vehicle tire as set forth in the preceding paragraph which will bring about that the pulling stresses introduced into the carcass within the area of the side walls of the tire will no longer be conveyed through those sections of the carcass which are adacent to the belt.

These and other objects and advantages of the invent on will appear more clearly from the following specification 1n connection with the accompanying drawing, in which:

FIG. 1 is an isometric view and partly a section showmg a raw tire made in conformity with the flat band method.

FIG. 2 is a diagrammatic section of a pneumatic tire made from the raw tire of FIG. 1 and placed under operational pressure.

A pneumatic vehicle tire according to the present invention is characterized primarily in that those sections of the strength carriers which face the belt and form the carcass are, in inflated condition of the tire, free from Patented Sept. 5, 1972 ice pulling stresses. Advantageously, the said sections are in the operative condition of the tire upset or compressed and in particular by about from 10 to 50% of the original length. Such a design of the carcass brings about that the pulling stresses introduced into the carcass within the range of the side walls of the tire are no longer conveyed through those sections of the carcass which are adjacent to the belt but are by those sections of the carcass which extend to the side walls of the tire induced into the marginal portions of the belt which as a result thereof is subjected to a correspondingly large pull prestress in the transverse direction of the tire with the result that the lateral stabilizing property of the belt will be greatly increased.

Referring now to the drawing in detail, the tire carcass 1 consists primarily of pull-resistant thread-shaped reinforcing inserts 2, for instance threads, wires, strands, and

the like, which extend approximately at a right angle with regard to the circumferential direction of the tire and which are firmly anchored on and looped around the bead cores 3 and extend in uninterrupted manner from bead to bead. The belt 4 surrounds the carcass in the form of an annular band with a fiat rectangular cross section. The said belt 4 consists of two or more layers 5 of parallel pull-resistant reinforcing inserts or strength carriers similar to the reinforcing inserts 2, which in the condition of the raw tire shown in FIG. 1 form an angle of approximately 30 to 40 with the circumferential direction of the tire. In a manner known per se the threads, wires, strands or the like of one layer cross those of the adjacent layer in a symmetric arrangement with regard to the circumferential direction of the tire.

FIG. 2 shows the pneumatic tire made according to FIG. 1 as mounted on a rim 6. The hollow chamber defined by the tire and the rim is under a superatmospheric pressure, for instance a pressure of two atmospheres above atmospheric pressure. The geometric length of the reinforcing inserts 2 forming the carcass 1 is designated with the letter L.

When building up the raw tire according to FIG. 1, that portion of the carcass 1 or of the carcass forming reinforcing inserts located between the heads 3 will have a length L' which is greater than the length L according to FIG. 2. When the raw tire according to FIG. 1 is curved to form the tire, the raw tire will increase in diameter. The diameter of the belt 4 will be greatly increased while the angle of the threads or the like forming the layers 5 will be reduced to an angle of approximately from 15 to 25. With this increase in diameter, also the width B decreases by approximately 20% to the width b. Inasmuch as the length L is greater than the length L, that section 1' of the carcass 1 which is directly adjacent to the belt 4 undergoes an upsetting or compressing action which corresponds to or is dependent on the decrease in the width of the belt 4 during the increase in the diameter of the latter.

When, after the tire has been completed, its hollow chamber 7 is subjected to pressure, the section 1' will be tension-free and may even be upset or compressed. The forces 8 caused by the tire inner pressure are therefore not conveyed through the section 1' but through the belt 4. The flow of forces is indicated by the arrows 9. The thus effected transverse tension of belt 4 brings about that belt 4 will be able to produce correspondingly larger reaction forces against the lateral forces which occur when the tire passes through a curve. Consequently, at the time the lateral forces are effective, the transverse deformation of the tread strip zone will be less.

It may additionally be mentioned that the transmission of the forces from the reinforcing inserts 2 to the marginal portions of the belt and vice versa is effected at 10 through the intermediate rubber layers vulcanized to the marginal portions of the belt.

What I claim is:

1. In a method of making a belted pneumatic tire while employing a carcass built up according to the flat band method and having beads arranged at opposite marginal portions and also having strength members extending from bead to bead, the steps of: building up a belt of a plurality of layers of rubberized strength members so that the strength members extend at an acute angle with regard to the circumferential direction of said belt while the strength members of one layer form an image to the strength members of the adjacent layer, said strength members of said belt extending from one side to the opposite side of said belt, placing said belt flat upon said carcass, curving the thus formed belt and carcass structure, said belt interacting with said carcass to place the side wall strength members of the carcass and the belt under tension while compressively shortening said carcass strength members between said side walls by transverse contraction of said belt, and vulcanizing the same during interaction between said carcass and said belt, the length of said carcass strength members being so selected that the said length prior to the curving of the belt structure is longer than the length of the carcass strength members in the vulcanized condition of the tire when relative to said carcass there is compressive shortening of predetermined sections of said carcass strength members making the same locally free of pulling tension thereon in the finished tire.

2. A method according to claim 1, in which those sections of the carcass which are adjacent to and face the belt are compressed by from on the order of 20 to 50% with regard to the length of the strength members prior to curving the belt and carcass structure accompanied by reduction of acute angle of said strength members with regard to circumferential direction of said belt during prerequisite reduction of finished tire width and increase in finished tire diameter.

References Cited UNITED STATES PATENTS 3,409,492 11/1968 Yoe 156-133 X 1,689,793 10/1928 Midgley 156-123 X STEPHEN C. BENTLEY, Primary Examiner 

